Lubrication systems perform the task of supplying individual lubrication points or a group of lubrication points, such as at least one part of a bearing, joint, gear, and/or any other part(s) of one or more machines, with a varying or non-varying amount of liquid lubricant to ensure that the lubrication points are lubricated. Over-lubrication or under-lubrication may have negative influence on a machine component's service life and may result in machine breakdown.
In lubrication systems for instance for bearings, there is a need for supplying a fluid lubricant, such as oil or grease, to the bearings from a reservoir via pipes of the lubrication system.
Various types of pump assemblies are known for use in lubrication systems. For example, a barrel pump can be used for transporting the fluid lubricant from a reservoir to a pipe of the lubrication system. Besides supplying the fluid lubricant to a component during operation, the pump assembly can also be used when the component/bearing or bearing house is re-filled with fluid lubricant during service/installation.
International PCT-publication WO 2014/127912 describes a pump assembly for pumping a fluid lubricant. The pump assembly provides a pump mechanism configured for pumping a fluid lubricant and a drive mechanism. The drive mechanism provides a pneumatic cylinder housing configured for being powered by an air source, the pneumatic cylinder housing accommodating a movable piston for operating the pump mechanism. The drive mechanism of the pump assembly also provides an electric switch for detecting a position of the piston, an electric valve unit that is configured to shift the direction of movement of the piston upon an activation of the valve unit, and an electric control unit operatively connected to the switch and to the valve unit, wherein the control unit is configured for controlling the activation of the valve unit in response to a detection of the position of the piston by the switch.
Thus, this known pump assembly is dependent on and connected to a pressurized air source as well as a power source for the operation thereof, and the piston direction change mechanism is complex and is subject to potential malfunction due to lack of power supply to the pump assembly.
Known pump assemblies having a pneumatic drive mechanism are typically equipped with a complex direction change mechanism, for the movable piston, comprising springs which are subject for wear and will break and the pneumatic drive mechanism requires regular maintenance and regular exchange of springs in order not to jeopardize the operation of the pump assembly.